Electric switch



1956 T. E. CURTIS 2,760,019

ELECTRIC SWITCH MW )I I: 'l' i .0 I

I 2 i v 2| 1 I W 0 E H m i" E h w I'm THOMAS E. CURTIS ATTORNEY Aug. 21, 1956 T. E.. CURTIS ,7

ELECTRIC swrrca Filed Feb. 11, 1954 2 Sheets-Sheet 2 I l2b 7 l2 so I 30 ll XI f I. 28 I fl '27 I 2 28a 28 29a Z3 26 19o: 4 24 f 32 26 ff! Y J 3| FIG. 3 4

INVENTOR THOMAS E. CURTIS ATTORNEY ELECTRIC swrrcn Thomas E. Curtis, Hampton, Ga., assignor to Southern States Equipment Corporation, a corporation of Georgia Application February 11, 1954, Serial No. 409,655

2 Claims. (Cl. 200-48) This invention relates to electric switches. and more particularly to high voltage switches of the type wherein a switch blade is rotated about its longitudinal axis to establish high pressure contact with the spaced elements of a fixed jaw contact and which is mounted to swing bodily relative to the jaw contact. While not so limited, the invention is particularly adapted for use in conjunction with switches of the two insulator typ e wherein one insulator stack supports the fixed jaw contact and the other insulator stack supports the switch blade and in addition is rotatably mounted to impart the desired operating movement to the switch blade.

Since in switches of this type the rotatable insulator stack must rotate the switch blade about its longitudinal axis and also impart bodily swinging movement to the blade, it is possible for the operator to apply an operating force during closing of the switch which is great enough to cause the blade to rotate about its longitudinal axis before swinging into the space between the jaw contacts, particularly when the switch blade is-of a high inertia construction. When this happens the switch obviously cannot perform a proper switch closing operation and it may be difiicult to restore the parts to their normal positions.

An object of this invention is to provide an improved switch of the type wherein a switch blade is rotated about its own axis and arranged for swinging movement relative to a cooperating fixed jaw contact and in which provision is made to tend to prevent premature rotation of the switch blade about its longitudinal axis during closing and which is characterized by a smooth manner of operation.

Another object of this invention is to provide an electric switch having an improved over-center toggle which is spring-biased in such a way as to aid materially in establishing high pressure engagement between spaced jaw contacts and the switch blade.

The invention, in one form as applied to a two insulator switch, comprises a fixed jaw contact, a switch blade rotatable about its longitudinal axis and mounted for swinging movement relative to the fixed contacts, a crank movable in a plane parallel to the plane of swinging movement of the blade, and strong over-center toggle means interconnected between the blade and the crank for establishing an operative relationship therebetween.

For a better understanding of the invention reference may be had to the following description taken in conjunction with the drawings in which Fig. 1 is a side view of an electric switch embodying the invention; Fig. 2 is an enlarged view partially in section of bearing means forming a part of the invention together with crank and over-center toggle means associated therewith; Fig. 3 is an enlarged view partially in section of the over-center toggle structure forming an element of the invention, the parts being shown in the positions which they occupy at the instant the switch bladeengages or diszengages the jaw contacts; and in which Fig. 4 is a view similar to Fig. 3 showing the parts in the positions which they occupy when the switch is fully closed.

With reference to Fig. l, the numeral 1 designates a ie States Patent metallic base of conventional structural steel construction and adapted for mounting on suitable supporting structure. An insulator stack 2 is secured to one end of the base 1 by suitable means such as bolts 3 and a similar insulator stack 4 is secured to the other end of base 1 by suitable means such as bolts 5. Secuned atop the insulator stack 2 is a jaw contact 6 formed integrally with the terminal stud 7. As shown bolts 8 constitute means for attaching parts 6 and 7 to stack 2. Similarly, a jaw contact 9 together with the terminal stud 10 formed integrally therewith are secured atop the insulator stack 4 by means of bolts 11. The jaw contacts 6 and 9 are bridged by a suitable switch blade 12 mounted for swinging movement about the central bearing means generally designated at 13. Bearing means 13 is secured atop insulator stack 14 by any suitable means such as the bolts 15. Insulator stack 14 is rotatably mounted on the bearing structure generally designated at 16 which structure in turn is secured to base 1 by any suitable means such as the bolts 17. Secured to the lower end of insulator stack 14 is an operating rod 18 by which rotating movement is imparted to the insulator stack 14 thereby to impart swinging movement to switch blade 12.

Switch blade 12 is mounted on bearing means 13 for swinging movement relative to jaw contacts 6 and 9 and in addition is arranged to rotate about its longitudinal axis thereby to engage the jaw contacts 6 and 9 by high pressure contact similar to the manner in which the switch blade engages the jaw contacts in United States Patent 2,520,036 Gussow et al., granted August 22, 1950, and assigned to the assignee of this invention. The particular construction of the bearing means 13 and of the elements associated therewith can best be seen from Fig. 2.

From Fig. 2 it will be observed that bearing means 13 comprises a rotatable bearing element 19 and a rotatable bearing support 21. Element 19 has a vertically disposed hollow tubular portion 1% to which is secured a cover plate 1% by means of bolts which together with the upper horizontally disposed portion of the bearing element 19a forms a horizontally disposed tubular enclosing structure in which the switch blade 12 is rotatably mounted. Cover 19b and the horizontal portion of the rotatable bearing element 19 are provided with an internal peripheral groove 1% in which a pin 12a mounted in the blade 12 is arranged to move. Thus pin 12a, being laterally disposed in the switch blade 12, prevents endwise motion of blade 12 relative to the bearing means 13. For the purpose of minimizing friction between the switch blade 12 and bearing means 13 suitable bearing elements 20 are mounted on the blade bearing surfaces within the left-hand and right-hand extremities of the horizontally disposed portion of rotatable bearing element 19. Preferably, bearing elements 20 should comprise a solid bearing substance impregnated with a lubricating fluid. From the description thus far it will be understood that the switch blade 12 is rotatable about its own axis but that switch blade 12 is prevented from end-wise movement relative to bearing means 13 due to the action of pin 12a riding in internal groove 19d.

The switch blade 12 is arranged for swinging movement. about the axis of insulator stack 14. To this end the rotatable bearing support 21 comprises a hub portion secured to stack 14 by bolts 15 and formed integrally with crank 23, a stud 21a constituting an axial extension of the hub of rotatable bearing support 21 and nut 26 threadedly engaging stud 21a. Bearing elements 22 are disposed about the bearing surfaces of stud 21a and engage the adjacent portions of rotatable bearing element 21 which are referred to as main bearing surfaces.

For the purpose of imparting rotary movement to the switch blade 12 relative to its own axis and thereafter for imparting swinging movement to the switch blade during switch opening operations, for example, the crank 23, formed integrally with the hub of rotatable bearing element 2]. at its right-hand extremity is operably related with a toggle structure generally designated by the numeral 24. Thus with the switch in the closed position an operating force applied to operating arm 18 imparts rotary movement to crank 23 thereby to rotate switch blade 12 about its own axis to cause the ends of the switch blade to disengage the jaw contacts 6 and 9 and thereafter to impart switch opening swinging movement to the switch blade 12. Stop 9a starts switch rotation in known manner.

The overcenter toggle 24 could be constructed in any number of ways. As shown in detail in Figures 3 and 4, the toggle comprises the socket structure 25 formed within the extremity of the crank 23, a ball 26a secured by stud 27 to yoke 28 together with cap 29 arranged with respect to the socket 25 and ball 26a so as to form a ball and socket connection. It will be observed from Figures 3 and 4 that cap 29 is provided with a slot 29a in which the stem 27 is movable. Furthermore, it will be observed that the yoke 28 is provided with a lower skirt portion 28a arranged to shield the slot 29a from the effects of weather. Yoke 28 is pivotally connected at its upper end to blade 12 by pin 30. If desired, the blade 12 may be provided with a reinforcing sleeve 12b at the point on blade 12 where the pin 30 is mounted. Ball 26a is biased upwardly by compression spring 31 disposed within the socket 25 and arranged to exert an upward force on the plunger 32 mounted within the socket 25 thereby to tend to bias the toggle toward its overcenter positions.

For the purpose of arresting the swinging movement of blade 12 about the insulator stack 14 relative to the jaw contacts 6 and 9 during switch closing operations, each of these contacts is provided with a stop element 33. Upon engagement of the blade 12 with the stop elements 33 swinging movement of blade 12 is arrested and thereafter rotating movement of blade 12 about its own axis is effected.

Assuming that the switch is in the closed position, represented in Fig. 4, opening force applied to operating element 18 causes the crank 23 and socket 25 to move toward the left as viewed in Fig. 4 thereby to compress spring 31 and to impart rotary movement to switch blade 12 relative to its own axis. When the opening operation has progressed until the parts occupy the positions shown in Fig. 3, the spring 31 occupies its position of maximum compression, and the toggle comprising the ball and socket elements 26a and 25 together with yoke 28 occupies a straight line or dead center position. The dead center position of the toggle is made to be coincidental with the point of initial disengagement of the tips 120 of blade 12 during a switch opening operation. Thus assuming that the switch is being closed and that the blade has been swung about insulator stack 14 until it has engaged stop 33, the parts occupy the positions shown in Fig. 3. Thereafter continued operating movement imparted to operating arm 18 causes suitable contact pressure to be established between the blade tips 12c and the jaw contacts 9 and 6. From Fig. 3 it will be observed that the latter stages of the closing operation are accomplished with a minimum of operating efiort due to the fact that the twisting movement of blade 12, which establishes high pressure engagement between contact tips 120 and jaw contacts 9 and 6, is aided by the action of spring 31 due to the fact that the dead center position of the toggle comprising elements 25, 26a and 28 is chosen to coincide with the initial point of contact of switch blade tip 120 with the jaws of contacts 6 and 9 according to a feature of the invention. Thus high pressure contact between the current carrying elements of the switch is achieved with a minimum of operating eflort. Since the spring 31 assists the operator in performing switch closing .4 operations this spring can be made unusually strong and will therefore tend to prevent the toggle 24 from swinging overcenter prematurely during a closing operation, it being understood that if the moving parts are sufficiently heavy and if the operator should apply a sufiiciently strong force to the operating element 18, the switch blade 12 might be caused to rotate about its own axis before the full swinging movement of the blade 12 is effected during closing. Of course, should this happen it would be impossible to close the switch and furthermore it might be difficult to restore the parts to their normal po sitions without undue interruption of service and an expensive maintenance operation might be required. The blade of the above arrangement obviously is not likely to rotate about its own axis prematurely. Furthermore, the switch may be operated with a minimum of operating force.

While I have shown and described a particular embodiment of the invention, I do not wish to be limited thereto and intend in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric switch comprising a fixed contact having a pair of spaced jaws, a switch blade rotatable about its longitudinal axis and mounted for swinging movement relative to said fixed contact, said blade having a contact tip adapted freely to enter the space between said jaws and thereafter to engage said jaws by pressure contact in response to rotation of said blade about its longitudinal axis during a switch closing operation, stop means engageable by said blade for limiting swinging movement thereof, a crank arranged to swing in a plane substantially parallel to the plane of swinging movement of said blade about a center which is substantially coaxial with said bearing means, toggle means interconnected between said crank and said blade and movable from one overcenter position through dead center to another overcenter position in coordination with engagement of said blade with said stop means during a switch closing operation, said toggle being approximately at its dead center position when said blade tip initially engages said jaws so that further rotation of said blade during closing is aided by said spring means, and spring means biasing said toggle means so as to tend to maintain said toggle means in each of its overcenter positions so as to tend to prevent rotation of the blade during swinging movement thereof and when in the closed position.

2. An electric switch comprising a fixed contact having a pair of resilient spaced jaws, a movable contact blade rotatable about its longitudinal axis and mounted for swinging movement relative to said fixed contact, said blade having an end portion adapted freely to enter the space between said jaws and thereafter to engage said jaws by pressure contact in response to rotation thereof about its longitudinal axis, means including toggle means for imparting swinging movement to said blade to move said end portion into the space between said jaws and thereafter for rotating said blade about its longitudinal axis during closing of said switch, said toggle means being movable from one overcenter position through dead center to another overcenter position, spring means biasing said toggle means toward its overcenter positions for preventing rotation of said blade about its longitudinal axis during swinging movement thereof and said toggle being approximately at its dead center position when said end portion of said blade initially engages said jaws so that further rotation of said blade during closing is aided by said spring means.

References Cited in the file of this patent UNITED STATES PATENTS 

